Originally Posted by ucfchris844
My girlfriend had an m3 and I changed her oil every 8,000 miles and the engine built up with sludge and we had to trade it off. I have always changed my oil every 3,000 miles. A $100 every 3,000 miles is cheaper then rebuilding an engine.
the M3 motor slugged??? you must of been using regular oil and not synthetic. Synthetic oils don't sludge, at least that's what I understand. 8,000 miles is a bit much for oil change intervals on a performance engine. I would change oil at 5,000 and use synthetic. 3,000 mile change is only necessary for regular dinosaur oil, it can't take too much heat, so it tends to break down and sludge up which probably means that you need to install some sort of oil cooler. Actually oil never really wears out, it just gets dirty.